In-medium chiral condensate beyond linear density approximation

Understand

In-medium chiral perturbation theory is used to calculate the density dependence of the quark condensate $<\bar qq>$.

• The corrections beyond the linear density approximation are obtained by differentiating the interaction contributions to the energy per particle of isospin-symmetric nuclear matter with respect to the pion mass.
• Our calculation treats systematically the effects from one-pion exchange (with $m_\pi$-dependent vertex corrections), iterated $1\pi$-exchange, and irreducible $2\pi$-exchange including intermediate $\Delta(1232)$-isobar excitations, with Pauli-blocking corrections up to three-loop order.
• We find a strong and non-linear dependence of the ``dropping'' in-medium condensate on the actual value of the pion (or light quark) mass.